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I have a nomogram that allows the conversion of a wine's residual sugar from degreesBrix(the RS measurement that's easy to make) to weight/% (the amount of RS we actually taste) as a function of the wine alcohol%. Generally I use it when someone expresses the RS in Brix and want to know the w/% RS.
Does anyone know if this very useful nomogram is available online?? I can't seem to find one. Hard to believe Google as actually failed me.
Tom

Tom, I'm not sure I've got the nomenclature down correctly; is this what you mean?

-The term must density (or weight) is more useful to winemakers since it gives a measure of grape ripeness by components dissolved in the must. Since ~90% are reduceable sugars, this is a measure of potential alcoholic strength as well. The French use the scale Baume( equivalent to %alcohol volume/volume). The USA and Oz use the Brix scale (weight/volume), and the Germans use the Oeschele scale (weight/weight or the number in thousandths of the specific gravity eg 1.090=90 Oeschele). That just about describes the number of viewpoints in NATO these days.
Since each % alcohol derives from a known quantity of sugar, nomogram scales can be made to compare these.
Basically
9 Baume= 16 Brix=65 Oeschele=8%alcohol
13 Baume=22 Brix=95 Oeschele= 12%alcohol
14 Baume=26 Brix=110 Oeschele=14%alcohol
15 Baume=28 Brix=120 Oeschele=15%alcohol

Bob,
I'm referring not to must weight in juice (degBrix approx = weight% sugar), but the Residual Sugar in WINE. Huge difference. In juice, the primary/only solvent is water.
In wine, you got lower-density alcohol (presumably primarily ethanol) that mucks things up. So when you take a density measure for RS in wine (degBrix), you have to account for the amount of alcohol in there lowering the density. You can have a wine with 16% alcohol (i.e. your typical Zinfandel these days) and 1% (by weight) RS and the RS on the Brix scale will be -.62839173857 degBrix RS. Made up numbers).
The nomogram I have, you set a ruler on one scale at % alc, the other at the RS (deg Brix), and you read off the % (by weight) RS on the middle scale.
Why..... I bet I could even write a software package that would do the calculation. Sell it for $100 each. ....Make BIG $$$$'s....quit my day job.....buy ScreamingEagle... the potential is unlimited!! Tom

Is the nomogram ruled in linear units (i.e., are all the tick marks on the scales evenly spaced)? If so, it's a simple linear equation that would be trivial to code up in Excel or some other spreadsheet software, or to throw into an online calculator.

I'm pretty conversant in molar and molal solutions due to my distant past training in biochemistry, but I'm not sure how that relates to degrees Brix or to %RS.

Ohhhh....not sure the issue is worth hours, John.
It is always (mildly) irrritating to me when the label expresses the RS in degBrix, because that's not what you taste. It's easy to measure that w/ a simple hydrometer, but it doesn't relate to what you taste on the palate. The actual weight% measurement of RS takes a little more lab work I believe.
So, it doesn't happen often, but I do see it on several labels a yr. So, now irritated as hell, I gotta go rummaging thru my files to dig up that nomogram and make the conversion myself.
That nomogram came from some oenology test or article and I don't know where. I know that I did have to extend the scale (it is a linear scale on the three scales) on the %alc side to go beyond 14% up to 18%.
Tom

I ask a simple question and get sucked into this discussion on RS in wine!!
I'm clueless as to what the Clinitest tablets are.
In an operating winery, they state the RS in wine either (not often, thankfully) as degBrix, or as weight% RS. I've never seen the RS expressed as volume%. How they measure the weight% RS in the enology lab, I have no idea but will try to remember to look it up in one of my enology texts when I go home. I also know that our sensitivity to RS in wine in NOT a function of the degBrix, but a function of the RS as weight%, simply because that's how the RS is stated. Whether our palate correlates more closely w/ RS as vol% than weight%...I haven't the foggiest. Now... that's ALL I know...I'm clueless about everything else w.r.t. RS.
Jeez.....I'm just a plain ol' simple lil' ol' country computational physicist... all this chemistry stuff is waaaaay over my head.
Tom (getting a bit testy on a Thurs morning)

TomHill wrote:I ask a simple question and get sucked into this discussion on RS in wine!! I'm clueless as to what the Clinitest tablets are. In an operating winery, they state the RS in wine either (not often, thankfully) as degBrix, or as weight% RS. I've never seen the RS expressed as volume%. How they measure the weight% RS in the enology lab, I have no idea but will try to remember to look it up in one of my enology texts when I go home. I also know that our sensitivity to RS in wine in NOT a function of the degBrix, but a function of the RS as weight%, simply because that's how the RS is stated. Whether our palate correlates more closely w/ RS as vol% than weight%...I haven't the foggiest. Now... that's ALL I know...I'm clueless about everything else w.r.t. RS. Jeez.....I'm just a plain ol' simple lil' ol' country computational physicist... all this chemistry stuff is waaaaay over my head.Tom (getting a bit testy on a Thurs morning)

Tom,

Think Zen, and all the sugar in the world--or in the wine--won't matter